SubMiniature version A (“SMA”) shell connectors are defined in military and trade specifications. Some of these connectors use the center conductor of the cable as the connector center contact, and the cable dielectric as the connector dielectric. Most coaxial connectors have separate contacts and dielectric inserts that hold the center conductor centrally within the connector. This connector is used primarily on a cable having an outer diameter of 0.141 inches and provides a low cost, very short microwave connector. Assemblies using this cable and connector combination generally are used to interconnect microwave modules mounted on printed circuit boards or microwave sub-assemblies.
An example of a standard, commercial shell-only SMA connector according to the prior art is shown in FIG. 1. A cable 10 is provided with a center conductor 14 surrounded by a dielectric 16. An outer conductor 12 surrounds the dielectric 16. The connector 20 is soldered on the outer conductor 12 of the cable 10 by applying solder 18 to the rear of the connector 20. The solder 18 then flows internally in the connector 20, between the connector 20 and the outer conductor 12, to complete an electrical path. The disadvantage of this construction is that a ring of solder is formed at the joint of the cable 10 and connector 20 at the rear of the connector 20. This limits where the cable 10 can be bent, thus preventing a tight bend at the rear of the connector 20 from being formed when necessary.
Another way to attach the connector to the cable is to solder the connector from the front of the cable at the connector interface. While this eliminates the solder build-up at the rear of the connector, solder instead builds up on the connector interface. The interface therefore must be machined by a separate operation during manufacture to eliminate the solder build up at the connector interface, where the male SMA connector would mate with a female SMA connector. This operation removes the gold plating on the connector interface and also tends to easily damage the center conductor of the cable, which projects outwardly.
A further, significant problem exists with either of these connector designs. After assembly, when the cable is twisted or bent, the cable dielectric can move forward and extend beyond the connector mating face (reference plane 60), and thus prevent proper mating with another connector.
The present invention addresses these shortcomings in in the prior art by eliminating the solder at the rear of the connector, eliminating the need to machine the interface, eliminating cable dielectric protrusion, and compensating for the interface capacitance caused by the mating of connectors with different inner and outer conductor diameters.